HTML/CSS Web Development is the foundational practice of building the front-end, or user-facing portion, of websites. This discipline involves using HTML (HyperText Markup Language) to create the essential structure and semantic meaning of web content, organizing elements like headings, paragraphs, and images into a coherent document. Complementing this structure, CSS (Cascading Style Sheets) is used to apply all visual styling, controlling everything from layout, colors, and typography to responsive design adjustments for different screen sizes, ultimately translating a design concept into a functional and accessible experience on the web.